Update FAQ (#313)

Make it clear that we actually use kibibytes, mebibytes, etc.

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>

diff --git a/FAQ.md b/FAQ.md
index a5da217235b45c7379a272a800b643e857fcd326..677842db03a352eb248627b00fbcc4310ec81d15 100644 (file)
--- a/FAQ.md
+++ b/FAQ.md
@@ -7,6 +7,7 @@
 [1.1.](#1_1) When I compile sysstat, it fails with the following message: `make: msgfmt: Command not found`  
 [1.2.](#1_2) When I try to compile sysstat, it fails and says it cannot find some include files.  
 [1.3.](#1_3) I don't understand why sysstat displays the time sometimes as `HH:MM:SS` and sometimes as `HH:MM:SS AM/PM`...  
+[1.4.](#1_4) What are the units actually used by sysstat commands?  
 
 **[2. Questions related to sar, sadc and sadf](#sar)**
 
@@ -128,6 +129,19 @@ Moyenne:          all      0,24      0,00     89,64      0,00     10,12
 As you can notice, the time format but also the date, the decimal point, and
 even some words (like "Average") have changed according to the specified locale.
 
+---
+
+1.4.<a name="1_4"></a> What are the units actually used by sysstat commands?
+
+
+A: Although sysstat commands use the following abbreviations: kB, MB, etc.
+as part of the metrics names (e.g. kB_read/s, wkB/s, or even sometimes with a
+lower 'b': kbmemfree, kbavail...), and the manual pages speak of kilobytes,
+megabytes, etc., we always actually refer to kibibytes (kiB), mebibytes (MiB),...  
+A kibibyte is equal to 1024 bytes, and a mebibyte is equal to 1024 kibibytes.  
+Metrics names have been defined many years ago. We don't modify them to avoid
+breaking third-party programs parsing sysstat commands' output.
+
 ---
 ### 2. Questions related to sar, sadc and sadf<a name="sar"></a>